#include <algorithm>
#include <vector>
using namespace std;
class Solution {
public:
  int arrayPairSum(vector<int> &nums) {
    sort(nums.begin(), nums.end());
    int res = 0;
    for (int i = 0; i < nums.size(); i = i + 2) {
      res += nums[i];
    }
    return res;
  }
};
